kernel/ksysfs.c

   1 /*
   2  * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which
   3  *                   are not related to any other subsystem
   4  *
   5  * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
   6  *
   7  * This file is release under the GPLv2
   8  *
   9  */
  10
  11 #include <linux/kobject.h>
  12 #include <linux/string.h>
  13 #include <linux/sysfs.h>
  14 #include <linux/module.h>
  15 #include <linux/init.h>
  16 #include <linux/kexec.h>
  17
  18 #define KERNEL_ATTR_RO(_name) \
  19 static struct subsys_attribute _name##_attr = __ATTR_RO(_name)
  20
  21 #define KERNEL_ATTR_RW(_name) \
  22 static struct subsys_attribute _name##_attr = \
  23         __ATTR(_name, 0644, _name##_show, _name##_store)
  24
  25 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)
  26 /* current uevent sequence number */
  27 static ssize_t uevent_seqnum_show(struct kset *kset, char *page)
  28 {
  29         return sprintf(page, "%llu\n", (unsigned long long)uevent_seqnum);
  30 }
  31 KERNEL_ATTR_RO(uevent_seqnum);
  32
  33 /* uevent helper program, used during early boo */
  34 static ssize_t uevent_helper_show(struct kset *kset, char *page)
  35 {
  36         return sprintf(page, "%s\n", uevent_helper);
  37 }
  38 static ssize_t uevent_helper_store(struct kset *kset, const char *page, size_t count)
  39 {
  40         if (count+1 > UEVENT_HELPER_PATH_LEN)
  41                 return -ENOENT;
  42         memcpy(uevent_helper, page, count);
  43         uevent_helper[count] = '\0';
  44         if (count && uevent_helper[count-1] == '\n')
  45                 uevent_helper[count-1] = '\0';
  46         return count;
  47 }
  48 KERNEL_ATTR_RW(uevent_helper);
  49 #endif
  50
  51 #ifdef CONFIG_KEXEC
  52 static ssize_t kexec_loaded_show(struct kset *kset, char *page)
  53 {
  54         return sprintf(page, "%d\n", !!kexec_image);
  55 }
  56 KERNEL_ATTR_RO(kexec_loaded);
  57
  58 static ssize_t kexec_crash_loaded_show(struct kset *kset, char *page)
  59 {
  60         return sprintf(page, "%d\n", !!kexec_crash_image);
  61 }
  62 KERNEL_ATTR_RO(kexec_crash_loaded);
  63 #endif /* CONFIG_KEXEC */
  64
  65 /*
  66  * Make /sys/kernel/notes give the raw contents of our kernel .notes section.
  67  */
  68 extern const void __start_notes __attribute__((weak));
  69 extern const void __stop_notes __attribute__((weak));
  70 #define notes_size (&__stop_notes - &__start_notes)
  71
  72 static ssize_t notes_read(struct kobject *kobj, struct bin_attribute *bin_attr,
  73                           char *buf, loff_t off, size_t count)
  74 {
  75         memcpy(buf, &__start_notes + off, count);
  76         return count;
  77 }
  78
  79 static struct bin_attribute notes_attr = {
  80         .attr = {
  81                 .name = "notes",
  82                 .mode = S_IRUGO,
  83         },
  84         .read = &notes_read,
  85 };
  86
  87 decl_subsys(kernel, NULL, NULL);
  88 EXPORT_SYMBOL_GPL(kernel_subsys);
  89
  90 static struct attribute * kernel_attrs[] = {
  91 #if defined(CONFIG_HOTPLUG) && defined(CONFIG_NET)
  92         &uevent_seqnum_attr.attr,
  93         &uevent_helper_attr.attr,
  94 #endif
  95 #ifdef CONFIG_KEXEC
  96         &kexec_loaded_attr.attr,
  97         &kexec_crash_loaded_attr.attr,
  98 #endif
  99         NULL
 100 };
 101
 102 static struct attribute_group kernel_attr_group = {
 103         .attrs = kernel_attrs,
 104 };
 105
 106 static int __init ksysfs_init(void)
 107 {
 108         int error = subsystem_register(&kernel_subsys);
 109         if (!error)
 110                 error = sysfs_create_group(&kernel_subsys.kobj,
 111                                            &kernel_attr_group);
 112
 113         if (!error && notes_size > 0) {
 114                 notes_attr.size = notes_size;
 115                 error = sysfs_create_bin_file(&kernel_subsys.kobj,
 116                                               &notes_attr);
 117         }
 118
 119         return error;
 120 }
 121
 122 core_initcall(ksysfs_init);